From DE 102 48 355 A1, we know of an electrically driven camshaft adjuster with an adjusting transmission which can be designed as a double eccentric transmission or a double planetary transmission. The adjusting transmission has low friction as well as a high reduction ratio of, for instance, 1:250.
From DE 10 2004 038 695 A1, we know of another camshaft adjuster which has an inner eccentric transmission or a planetary transmission as the adjusting transmission. A planetary transmission is also a part of a camshaft adjuster known from DE 100 54 797 A1, whereby in this case the adjustment can be done hydraulically or electrically. DE 10 2011 004 077 A1 discloses a shaft transmission that is suitable for a camshaft adjuster. In general, shaft transmissions for camshaft adjusters can be designed as pot type gears or flat gears. For a shaft transmission this is a three-shaft-transmission.